Drying oils

ABSTRACT

THIS INVENTION RELATES TO THE PREPARATION OF A QUICK-DRYING BINDING AGENT, WHEREIN AN EPOXIDISED OIL IS REACTED WITH A POLYETHYLENICALLY UNSATURATED ACID AT 180*-270*C. AND THE REACTION PRODUCT IS SUBSEQUENTLY HEATED AT 260*350*C., UNTIL IT HAS REACHED A DESIRED VISCOSITY. PART OF THE UNSATURATED FATTY ACID IS DISTILLED OFF DURING THE LATTER HEATING STAGE. A PREFERRED BINDING AGENT HAS A VISCOSITY OF 20-200 POISES AT 20*C., AN ACID VALUE OF 6.0-12.0, A SAPONIFICATION VALUE OF 180-200 AND A REFRACTIVE INDEX OF 1,4830-1,4930 AT 20*C.

United States Patent 3,711,307 DRYING OILS Johannes Donatus von Mikusch-Buchberg, Hamburg, GerrNnaigly, assignor to Lever Brothers Company, New York,

No Drawing. Continuation of application Ser. No. 753,766, Aug. 19, 1968. This application Jan. 13, 1971, Ser. No. 106,271

Claims priority, application Germany, Aug. 22, 1967, P 16 68 769.7 Int. Cl. C08h 9/00 US. Cl. 106-243 6 Claims ABSTRACT OF THE DISCLOSURE Continuation of application Ser. No. 753,766 filed Aug. 19, 1968.

This invention relates to quick-drying binding agents for paints, varnishes, printing inks, cements, core binders and similar products and to a method for their manufacture.

The partial dehydration of epoxidised oleic acid and epoxidised oleic acid esters by reaction with saturated carboxylic acids or anhydrides with subsequent pyrolysis of the reaction product has been proposed. Conjugated dienes are obtained as the main end product of this process. It has also been proposed to dehydrate epoxidised linseed oil by pyrolysis in the presence of an acid catalyst, such as p-toluene sulphonic acid. Although a fairly rapid drying oil may be obtained by this process the films formed from it remain tacky for quite a long period and are therefore not suitable for practical use. We now provide a method for the manufacture of rapid drying binding agents which form hard, non-tacky films.

According to the invention there is provided a process for the preparation of a binding agent consisting essentially of the steps of (a) reacting an epoxidised oil possessing an oxirane oxygen content of 1-10 percent w./w with an amount of a polyethylenioally unsaturated fatty acid equal to 0.5-3.5 moles per mole of oxirane oxygen at a temperature between 180 and 270 C. and

(b) heating this reaction product at 260-350 C. until a desired viscosity is reached and 0.1-1.5 moles of polyethylenically unsaturated fatty acid per mole of oxirane oxygen originally present in the oil are removed.

Preferably, the epoxidised oils possess an oxirane oxygen content of 3-9 percent w./'w. and are reacted with 1.2-3.0 moles polyethylenically unsaturated fatty acid per mole oxirane oxygen, 0.5-1.5 moles of which are removed are removed during the pyrolysis treatment. A preferred pyrolysis temperature range lies between 270-330 C. The viscosity of the pyrolysed oil may vary from 10-1000 poises.

Of the many oils that are suitable as starting material for epoxidation, drying oils and semi-drying oils of the isolenic type (that is oils or mixtures of oils containing at least 50 percent w./w. polyunsaturated fatty acids having methylene interrupted double bonds) are preferred. Examples of such oils which are rich in linoleic and/or ice linolenic acid, are linseed oil, soybean oil, sunflower oil, safllower oil, hemp 'oil, tall oil, poppyseed oil and fish oil. Of these oils linseed oil is particularly preferred.

Artifically produced oils, such as isomerised linseed oil, dehydrated castor oil '01 tall oil fatty acid esters may also be used. Oils containing hydroxy fatty acids, such as castor oil and oils containing epoxy groups such as mallow oil are also suitable for epoxidation. Epoxidation can be carried out in a known manner, for example by the method described by T. W. Findley et al. in Journal of the American Chemists Society 67, pp. 412-414 (1945).

If naturally epoxidised oils are used which, like for instance vernonia oil (Vernonia anthelm'intica) already have an oxirane oxygen content of about 3.5-4 percent, there is no need for further epoxidation.

The polethylenically unsaturated fatty acids with which the epoxidised oils are reacted can be, for example, linseed oil fatty acids, soybean oil fatty acids, dehydrated castor oil fatty acids, tall oil fatty acids or technical linoleic acid (such as the linoleic acid concentrate from cotton seed oil, fish oil fatty acids or mixtures of these materials) Fatty acid mixture containing at least 50 percent by weight polyethylenically unsaturated fatty acids with conjugated double bonds are preferred. Either fatty acid mixtures containing at least 50 percent of these acids at the outset can be used or fatty acid mixtures which can be concentrated during the reaction by distillation of part of the saturated and mono-unsaturated fatty acids, can be used.

The fatty acids left uncombined after reaction with the epoxidised oils have to be removed or bound as far as possible for the sake of the drying properties of the binding agent. They can be Wholly or partially removed during or after the pyrolysis treatment by distillation under vacuum. They can also be bound after the pyrolysis treatment by reaction with a stoichiometric equivalent of a polyol such as glycerine or pentaerythritol or an epoxy compound such as an epoxy resin.

The reaction of the epoxidised oils with the polyethylenically unsaturated fatty acids takes place at temperatures between and 270 C. The reaction may be carried out at normal or reduced pressure and with or without an azeotropic solvent. An excess of polyunsaturated fatty acids per mole of oxirane oxygen in the epoxidised oil should be used in order to avoid such secondary reactions of the epoxy groups as ketonisation or ether formation. The reaction is preferably carried out at reduced (1-2 mm. Hg) pressure without a solvent or at normal pressure in the presence of a solvent, which permits the azeotropic removal of water. Xylene can be used for example. It is advisable to exclude atmospheric oxygen by using an inert gas, such as nitrogen or carbon dioxide.

The subsequent pyrolysis takes place at 260-350 C., preferably 270-330 C., and causes fatty acids to split olf with the formation of double bonds. Some of these double bonds are used up spontaneously under the pyrolysis conditions through polymerisation, resulting in increasing viscosity of the pyrolysed oil. On reaching the desired viscosity in the range of 10-1000 rpoises, depending on what the final product is to be used for, pyrolysis is discontinued.

The binding agent produced by the process of the invention preferably has a viscosity of 20-200 poises at 20 C., an acid value of 6.012.0, a saponification value of 180-200 and a refractive index of 1.4830-l.4930 at 20 C.

To obtain a binding agent of given viscosity by the method of the invention it is necessary to control the temperature of the reaction, the time of the reaction and the degree of epoxidation of the oil. For a given degree of viscosity, the higher the reaction temperature and the higher the degree of epoxidation of the oil, the greater will be the tendency for the fatty acids and the initial oil to polymerise. The reaction time may then be shortened. For example, under otherwise equal reaction conditions, when the starting oil used and the degree of epoxidation are the same, it takes several hours at a temperature of 280 C. to obtain the same viscosity as can be obtained in less than one hour, in some cases in only a few minutes, at 320 C.

The method according to the invention can be carried out either batchwise or continuously.

The binding agents produced by this method, which can be used in paints, varnishes, printing inks, cements and core binders are excellent quick-drying film formers, producing hard, non-tacky films. The advantage of the method according to the invention is that undesirable side-effects such as ketonisation and ether formation, which adversely affect the film properties, are largely avoided and the polyethylenically unsaturated fatty acids taking part in the reaction, some of which, under the reaction conditions applied, remain combined with the end product, contribute a great deal to the drying and film-forming properties of the end product. The yield of high grade products with good drying properties is thus increased so that the product is particularly economical.

The method'according to the invention is described in more detail below with the aid of examples, but it is by no means limited to these.

EXAMPLE 1 100 g. of a linseed varnish oil, epoxidised to an oxirane oxygen content of 4.4 percent.

was heated with 172 g. of distilled linseed oil fatty acid (acid va1ue=200; saponification va1ue=200; iodine value (Wijs)=185 .1) and 30 g. xylene in about 1 hour to a temperature of 250 C. This mixture was refluxed for 1 hour in a reflux condenser with a water separator at an internal temperature of 250260 C. At the end of the refluxing period the acid value of the reaction product had decreased to 39. The reaction product was then heated in 40 minutes to 307 C. and the xylene distilled ofi. In all, 3.5 g. of reaction water was collected in the receiver. The intermediate product obtained (260 g.) had an acid value of 48 and an iodine value (Wijs) of 145.

100 g. of the intermediate reaction product was heated for 45 minutes at 0.2-2 mm. Hg and a temperature of 300 C., during which time 25.0 g. of fatty acid distilled oil. The residue (74.1 g.) had a viscosity of 144 poises at 20 C. and dried in the presence of 0.2 percent cobalt siccative in 2% hours to a smooth, glossy film. The characteristic values of the pyrolised product were as follows:

Acid value 8.1 Saponification value 191.5 13 1.4-

Iodine value (Wijs) 20 1.4918

A coat of the product to which no siccative had been added dried with the frosting typical of tung oil.

EXAMPLE 2 750 g. linseed varnish oil epoxidised to an oxirane oxygen content of 4.0 percent,

1500 g. distilled linseed oil fatty acid and 375 m1. xylene further 7 ml. of water distilled over. The reaction product produced (2,288 g.) had an acid value of 45.

In a distilling flask fitted with a carbon dioxide delivery tube and a cooling receiver, 1,100 g. of the ester was heated under a vacuum of 2 mm. Hg to 280 C. in 1 /3 hours and kept at this temperature for 1 /2 hours, during which time 312 g. fatty acids and 47.5 g. first runnings containing xylene distilled 01f. 739 g. of a drying oil with the following characteristic values remained in the flask:

Viscosity poises at 20 C..- 77 Colour value (Pallauf) 50 71 1.4906 Acid value 6.3 Saponification value 195.5 Iodine value (Woburn) Q 152.0

An 80 percent solution in turpentine substitute, to which 0.3 percent lead and 0.03 percent cobalt siccative had been added, when applied with a 60 m doctor knife, had begun to dry after 45 minutes, was dust-dry (dry enough to prevent dust clinging to it) and dry right through after 3% hours. The film was harder than a similarly dried film of linseed'stand oil, also with siccative added and unlike the latter, was not tacky on the surface.

EXAMPLE 3 A mixture of 400 g. partially epoxidised linseed oilcontaining 4.1 percent of oxirane oxygen,

640 g. Scandinavian tall oil fatty acids (acid value=192; saponification value=l97; iodine value=150; carbonyl value=7) and 156 g. xylene Viscosity .poises at 20 144 a 1.4916 Acid value 9.7 Saponification value 193.5 Iodine value 118.2 Carbonyl value 6.8

In the presence of 0.2 percent cobalt siccative a film began to dry after 1% hours and was dust-dry after 2% hours. A linseed stand oil with a viscosity of about poises, to which a siccative had been added and which was tested in the same way, only began to dry after 3% hours and was dust-dry after 5 hours. The surface of the linseed stand oil film was still slightly tacky after three days, whereas the film for the product of this example not tacky at all.

EXAMPLE 4 g. of a partially epoxidised linseed varnish oil containing 4.1 percent oxirane oxygen was refluxed with 80 g. of a 70 percent technical linoleic acid fraction(acid value=;4; iodine value=134.8) and 33 g. xylene for 2 hours at 220 C., 1% hours at 250-270 and hour at 270-300 C. in a reflux condenser with a water separator, during which time the xylene distilled 01f. The

reaction product was subsequently heated during 16 .minutes to a temperature of 315 C. at 1-2 mm. Hg pressure,wh ereby 14 'g. freefatty acids distilled off. 164 g. of a drying oil residue with a viscosity of 32 poises at 20 C.

was obtained. The product dried more quickly than linseed oil but to a relatively soft film which is typical of oils rich in linoleic acid.

EXAMPLE 100 g. of an epoxidised soybean oil containing 5.5 per cent of oxirane oxygen (acid value=1.5; saponification value=182.4; iodine 'value=6.6; n P=1.4728; viscosity=4 poises at 20 C.) was heated for 7 hours at 160 220 C. with 100 g. of the 70 percent technical linoleic acid fraction used in Example 4.

32 ml. xylene was subsequently added and the mixture refluxed with a water separator, the internal temperature being increased to 262305 over 3 hours by slowly drawing off the xylene.

3 g. of reaction water was separated.

The reaction product was subsequently heated under a vacuum of 2 mm. Hg to an internal temperature of 315 C., during which time 20 g. of linoleic acid distilled over. The residue had the following characteristic values:

Acid value 11.7 Saponification value 194.3 Iodine value (Wijs) 90.5 r1 1.4837 Viscosity poises 42 47 g. of the oil obtained by extraction with petroleum ether of VernOnia anthelmintica seed (iodine value (Wijs) =105.5; acid value=36.5; saponification value =173.0; oxirane oxygen content=3.64 percent), was refluxed with 100 g. distilled linseed oil fatty acid (acid value=20l.5; saponification value=203.5; iodine value- (Wijs)=189.5) and 34.4 g. xylene.

After 3 hours at 200 C. the internal temperature was increased to 250 C. by drawing 01f xylene and the mixture refluxed for 2 hours at 250-255 C.

2.2 g. reaction water distilled oil.

The intermediate product obtained (acid value=62) was subsequently heated to 278 C. in 40 minutes at 1 mm. Hg pressure, whereby 52 g. fatty acid distilled off, and kept at 278 C.-284 C. for a further 50 minutes. The residue (90.3 g.) had the following characteristic values:

The residue dried to a smooth, non-tacky film in 2% hours when 0.3 percent lead and 0.03 precent cobalt siccative had been added to it. The initial oil on the other hand had no drying properties and a coat to which a siccative had been added was still completely liquid after 14 days. The reaction of epoxidised drying or semi-drying oils with 6 saturated 'fatty acids followed by pyrolysisneverleads to products which have the original drying properties of the oils before epoxidation, much less to products which dry more quickly as do the products of the present invention. The following test was carried out with lauric acid for purposes of comparison:

A mixture-of 500 g. epoxidised linseed oil containing 4.0 percent of oxirane oxygen,

750 g. lauric acid (acid value=282) and 250 ml. xylene was heated to boiling point in about 45 minutes in a reflux condenser fitted with a water separator. The mixture was refluxed for 4 hours at an internal temperature of -190 C., during which time 16.8 ml. reaction water accumulated in the water separator. Suflicient xylene was then removed to raise the boiling temperature to 250 C. and this temperature was then maintained for 3 hours, during which time a further 1.6 ml. reaction water distilled over. The remaining reaction product had an acid value of 71.4 and a saponification value of 245.8.

395 g. of the ester was then heated in a distilling flask under vacuum (2.5 mm. Hg) to 280 C. in 1% hours and kept at this temperature for 1 hour, during which time 130.2 g. lauric acid distilled over. The residue (263 g.) had an acid value of 4.2 and a viscosity of 10.5 poises. Even after 0.2 percent cobalt siccative had been added the residue dried only to the extent that a coat exposed to the air began to dry but remained tacky.

A further batch of 395 g. reaction product was heated to 280 C. at 1 mm. Hg pressure and kept at this temperature for 2% hours, during which time 166.6 g. lauric acid distilled off. The residue had an acid value of 2.8 and a viscosity of 31 poises and also dried incompletely.

A further 35 g. lauric acid was distilled off from the second residue at 1 mm. Hg in 3 hours at 280 C. The product had an acid value of 1.6 and a viscosity of 192 poises but did not dry to a non-tacky film even in 3 days; nor did a product with a viscosity of 590 poises obtained after a further hours heating at 280 C. of the third residue and distilling ofl of a further 7 g. lauric acid.

A 60 percent solution of the last sample in turpentine substitute, with 0.2 percent cobalt siccative, began to dry in 2 hours (1% hours) but even after 5 Weeks (24 hours) was still not dry according to the Garmsen glass bead test. The figures in brackets refer to a linseed stand oil which was tested in the same way. When it Was attempted to split off still more lauric acid from the product by further heating, the material gelled. In total, of the original 750 g. of lauric acid, less than 700 g. were recovered and the gelled product still weighed 551 g. (after allowance had been made for the samples taken); 69 g. of this must have come from the lauric acid added, as 18.4 g. of reaction water had been separated from the epoxidised linseed oil, so that only about 482 g. of the product came from the linseed oil.

What is claimed is:

1. A process for the preparation of a binding agent consisting essentially of the steps of (a) reacting epoxidised oil possessing an oxirane oxygen content of about 1-10 percent w./W., with amount of a polyethylenically unsaturated fatty acid equal to about 0.5-3.5 moles per mole of oxirane oxygen at a temperature between about 180 and 270 C. in the presence of an azeotropic solvent to form a reaction product, (b) distilling said solvent from said reaction product, and (c) heating said reaction product in the substantial absence of said solvent at about 260-350 C. until a viscosity of 10 to 1,000 poises at 20 C. is reached and about 0.1-1.5 moles of the unsaturated fatty acid per mole of oxirane oxygen originally present in the epoxidised oil have been split off.

2. A process as claimed in claim 1 in which the epoxidised oil is prepared from an oil containing at least 50 percent by weight of a conjugated polyethylenically unsaturated fatty acid having methylene interrupted double bonds.

3. A process as claimed in claim 1 in which the epoxidised oil is prepared from an oil selected from the group consisting of linseed oil, soya bean oil, sunflower oil, 'safilower oil, hemp oil, poppy seed oil, fish oil, isomerised linseed oil, dehydrated castor oil, tall oil and tall oil fatty esters.

4. A process as claimed in claim 1 in which the reaction product is heated at 260350 C. at 1-2 mm. Hg pressure.

5. A process as claimed in claim 3 in which the reaction product is heated at 260-350 C. at 1-2 mm. Hg pressure.

6. Aproces's as claimed in claim 1 in which the polyethylenically unsaturated fatty acid is selected from the group consisting of linseed oil fatty acids, soybean oil fatty acids, dehydrated castor oil fatty acids and tall oil fatty acids.

References Cited UNITED STATES PATENTS THEODORE MORRIS, Primary Examiner US. Cl. X.R. 260l8 EP, 18 PF 

